• Journal of Advanced Navigation Technology
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• v.14 no.2
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• pp.253-259
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• 2010

Wireless mesh network is flexible network like Ad hoc network or bluetooth together based on base station. But, wireless mesh network shows high packet loss and when TCP was created, however as it was design based on wired link, wireless link made more transmission error than wired link. It is existent problem of TCP congestion control algorithm that TCP unfairness and congestion collapse over wireless mesh network. When TCP operation occurs with the packet loss where is not the congestion loss, it brings the performance degradation which is serious. In this paper, in order to improve efficient TCP congestion control algorithm in wireless mesh network, we proposed that TCP can adaptively regulate the congestion window in wireless link.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.3-8
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• 2013

In this paper, we present an energy-efficient base station operation with base station sharing in wireless cellular networks. Firstly, cost functions are modeled related with the amount of energy usage and traffic load. We use game theory and formulate an energy bill game, where the players are the service operators which are operating base stations and their strategies are the bill of their base station energy consumption and hand-over traffic load to the others service operators. We show that the global optimal performance in terms of minimizing the energy costs is achieved at the Nash equilibrium of the formulated energy bill game. Simulation results confirm that the proposed approach can reduce the energy bill of the service operator, and show the relationship between the energy cost saving and various parameters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.558-564
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• 2021

With the recent introduction of 5G, electromagnetic radiation sources are spreading throughout life, so it is necessary to establish a citizen-centered electromagnetic safety management system. In particular, the beamforming method of the 5G antenna increases the power density measurement of electromagnetic waves by more than 10 times when the wireless base station is installed, so it is unreasonable to determine the safety by physical measurement. Therefore, it is necessary to determine the presence or absence of electromagnetic wave safety in daily life through a predictive method by calculation through systematic model analysis. In this paper, in order to check the possibility of a 5G wireless base station using an electromagnetic wave numerical analysis tool as a way to solve this problem, we compared the measured values of the actual base stations and the predicted values through the prediction model to compare the reliability. A method of constructing a real-time base station electromagnetic wave strength prediction evaluation system combined with software was also proposed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.426-429
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• 2006

A distributed healthcare monitoring system prototype for clinical and trauma patients, was developed, using wireless sensor network node. The proposed system aimed to measure various vital physiological health parameters like ECG and body temperature of patients and elderly persons and transfer his/ her health status wirelessly in Ad-hoc network, to remote base station which was connected to doctor's PDA/PC or to a hospital's main Server using wireless sensor node. The system also aims to save the cost of healthcare facility for patients and the operating power of the system because sensor network is deployed widely and the distance from sensor to base station was shorter than in general centralized system. The wireless data communication will follow IEEE 802.15.4 frequency communication with ad-hoc routing thus enabling every motes attached to patients, to form a wireless data network to send data to base-station, providing mobility and convenience to the users in home environment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.133-138
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• 2015

In this paper, we propose a method for improving the lifetime of the sensor network SEP through the wireless sensor network divided into two spaces by reducing the transmission distance of the cluster head in the layer in the distance. With reference to the position information of the node, the base station divides the layer based on the midpoint of the nearest node and the furthest distance away from the base station node. And the cluster head in the outer layer far from the base station is transmitted the data to the base station via the cluster head in the inner layer base station to transmit data. That is, we are proposed the layered SEP by reducing the transmission distance of the cluster head in the outer layer for the energy consumption to a minimum. The proposed algorithm is verified by comparison with the existing SEP.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.437-442
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• 2005

This paper deals with the measurement and analysis of radio characteristic of 424 MHz for using the automation of transmission and supply of electric power, ana automatic meter reading(AMR). Normally radio propagation characteristic is the base of system design, performance evaluation and choice of position of the base station in wireless communication. It is the most accurate way to design a base station through practical measurements, but it costs much time, money and engineers. So, we developed 424 MHz short range wave propagation model for AMR service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1C
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• pp.59-68
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• 2002

In this paper we issue some problems occurring when a mobile host moves from a base station to another in a wireless multicasting and propose a solution. In the case of not being in the same multicast group, the old base station will pre-forward data to neighboring base stations to avoid transmission delay. However, if other mobile hosts move at short interval, the old base station may retransmit the same dta to the same neighboring base stations. Also, the old base station should retransmit data if the new base station has already discarded data even if the new base station is a member of the multicast group. In this paper we propose called Information Exchange Scheme (IES). In this scheme, each base station exchanges indirectly the data delivery information with the rest of the base stations in the same multicast group for efficient and reliable multicast and pre-forwards data not retransmitting the same data for minimizing transmission delay when a mobile host moves. We also present how IES is efficient by analyzing and simulating.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.500-511
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• 2003

To prevent performance degradation of TCP due to packet losses in the smooth handoff by the route optimization extension of Mobile IP protocol, a buffering of packets at a base station is needed. A buffering of packets at a base station recovers those packets dropped during handoff by forwarding buffered packets at the old base station to the mobile user. But, when the mobile user moves to a congested base station in a new foreign subnetwork, those buffered packets forwarded by the old base station are dropped and the wireless link utilization performance degrades due to increased congestion by those forwarded packets. In this paper, considering the case that a mobile user moves to a congested base station in a new foreign subnetwork, we propose an Implicit Priority Packet Forwarding to improve TCP performance in mobile networks. In the proposed scheme, the old base station marks a buffered packet as a priority packet during handoff. In addition, RED (Random Early Detection) at the new congested base station does not include priority packets in queue size and does not drop those packets randomly based on average queue size. Simulation results show that wireless link utilization performance of mobile hosts can be improved without modification to Mobile IP protocol by applying proposed Implicit Priority Packet Forwarding.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.1
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• pp.39-45
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• 2012

In this paper, a distributed 2-hop routing algorithm is proposed. The main purpose of the proposed algorithm is to reduce the overall power consumption of each sensor node so that the lifetime of WSN(wireless sensor network) is prolonged. At the beginning of each round, the base station transmits a synchronization signal that contains information on the priority table that is used to decide whether each sensor node is elected as a cluster head or not. The priority table is constructed so that sensor nodes closer to half energy distance from the base station get the higher priority. 2-hop routing is done as follows. Cluster heads inside half energy distance from the base station communicate with the base station directly. Those outside half energy distance have to decide whether they choose 2-hop routing or 1-hop routing. To do this, each cluster head outside half energy distance calculates the energy consumption needed to communicate with the base station via 1-level cluster head or directly. If less energy is needed when passing through the 1-level cluster head, 2-hop routing is chosen and if not, 1-hop routing is chosen. After routing is done each sensor nodes start sensing data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.1069-1084
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• 2011

This paper considers an optimal base station clustering problem for designing a mobile (wireless) communication network. For a given network with a set of nodes (base stations), the problem is to optimally partition the set of nodes into subsets (each called a cluster) such that the associated inter-cluster traffic is minimized under certain topological constraints and cluster capacity constraints. In the problem analysis, the problem is formulated as an integer programming problem. The integer programming problem is then transformed into a binary integer programming problem, for which the associated linear programming relaxation is solved in a column generation approach assisted by a branch-and-bound procedure. For the column generation, both a heuristic algorithm and a valid inequality approach are exploited. Various numerical examples are solved to evaluate the effectiveness of the LP (Linear Programming) based branch-and-bound algorithm.